The invention relates to a blooming protection for a night vision device or nightsight having an objective mounted in a tube.
When using a nightsight having high residual light gain to observe a scene at night, blooming and screening effects occur when there are light sources within the field of view. Associated therewith is a reduction in the contrast of the overall field of observation and increased difficulty in reading information displayed in the field of view of the nightsight.
A nightsight having an image intensifier tube is disclosed in U.S. Pat. No. 4,582,400 which is incorporated by reference.
DE-33 13 899 A1 discloses a device for viewing a luminous indicating instrument, which can also be viewed in darkness using a nightsight having high residual-light gain. In order to prevent blooming in this case, a first optical filter is arranged on the viewing side in front of the indicating instrument and a second optical filter is arranged in front of the photocathode of the nightsight, these filters having specific transmission properties as a function of the wavelength, which properties are matched to one another. The second filter which prevents the blooming comprises an A1-Sb layer which is vapor deposited onto the photocathode carrier of the image-intensifier tube.